There are a number of books on a shelf. If one book is the 4th from the left and 6th from the right, how many books are on the shelf?

In the image given, you can find several triangles. Can you count them all?

What has one letter and starts with an E?

The more of this there is, the less you see. What is it?

If eleven plus two equals one, what does nine plus five equal?

A dead body is found outside a multi-story multinational company. The case is reported and a homicide detective is called on the crime scene.

He looks at the body and then towards the building. From the position of the body, it is evident that the victim committed suicide. He goes to the first floor of the building and then walks in the direction of the dead body, opens the window and toss a coin in the air.

He goes to second floor and again repeats the process. He keeps doing this till he is done on all the floors. Then he returns back to the floor and tells his team that it is a murder.

How in heaven did he deduce that?

At a bar, three friends, Mr Green, Mr Red and Mr Blue, were having a drink. One man was wearing a red suit; one a green suit; and the other a blue suit. 'Have you noticed,' said the man in the blue suit, 'that although our suits have colours corresponding to our names, not one of us is wearing a suit that matches our own names?' Mr Red looked at the other two and said, 'You're absolutely correct. What colour suit is each man wearing?

Can you find out the missing number?

? 4 5 3 5

9 5 7 10 3

I am a type of word that is spelt incorrectly or used differently, on purpose for humour. What am I?
Hint 1: You can find me in a joke.
Hint 2: I am a play on words.

I have cities, but no houses. I have mountains, but no trees. I have water, but no fish. What am I?